But SingPost marketing vice-president Steve Ng got the most attention from journalists. He talked about the mysterious "vandalism" of SingPost's mailboxes between New Year's Day and Monday.

He said it was part of a "viral marketing initiative to create greater awareness and buzz on self-expression through art and sports", and was actually a lead-up to Stamp 2, a mailbox art competition which was part of Express Yourself.

An earlier art competition called Stamp was held in 2007. Mr Ng said: "We would like to apologise for the undue alarm and inconveniences caused to all parties. SingPost would like to thank the public for their interest, concern and public spiritedness."

THIS MAILBOX ROCKS: A SingPost mailbox, which was the winning entry in the Open category for Stamp, a mailbox art competition held in 2007.

Over the next week, Mr Ng said local artists would repaint the six mailboxes to highlight Stamp 2.

After Mr Ng's speech, the mysterious "vandal", who was named the "Inkman", appeared.

The man, who wore a black hat, a green camouflage net over his face, white long-sleeved shirt, black tie and black pants, stood still while holding a can of paint and two paintbrushes in his black-gloved hands. Then the journalists fired questions at Mr Ng.

Why wasn't an application made for a police permit? Mr Ng said SingPost made an application and was told that there was "no requirement for a public licence".

He added that SingPost's public relations agency had filed a report at a Neighbourhood Police Post before Christmas.

But when asked what the "report" was, he said: "The agency told the police that a pre-launch event was going to be held, that it would involve street art on mailboxes at specified locations, and that the event would have a youth-based theme."

Mr Ng confirmed that "they did not tell police all the information" such as the involvement of a masked man or that there would be graffiti.

He said this was what SingPost had meant when it told The New Paper that it had lodged police reports.

When The New Paper pointed out that a police report was very different from what Mr Ng had said earlier, Ms Tay Poh Choo, SingPost's corporate communications vice-president, declined to comment.

As the questions were fired at Mr Ng, his calm demeanour turned anxious.

"Why did SingPost not tell the press earlier that this was a publicity stunt?"

His reply: "We told the corporate communications department to keep mum to the media because we did not want to reduce the impact of today's event. But we should have engaged the media earlier."

Looking anxious

By this time, Mr Tan and Mr Goh were also looking anxious. When asked about his role in the stunt, Mr Tan said the focus of the press event was the announcement of the partnership between SingPost and Singapore 2010 YOG. He repeated SingPost's apology, adding that it did not intend to cause public alarm.

The emcee tried to draw everyone back to the main agenda by asking if anyone had any questions related to the YOG.

But still, questions on the mailboxes flew thick and fast. When The New Paper asked Mr Ng if it was a bad idea,he said it had been "a good out-of-the-box idea".

Mr Teo Ser Luck, Senior Parliamentary Secretary in the Ministry of Community Development, Youth and Sports, said it was not for him to judge if SingPost had gone overboard in its handling of the "vandalism".

He said: "They are the experts and, hopefully, they should know if they have gone overboard.

"As a member of the public, I would say that in everything they (SingPost) do, we hope they will not disturb others. But if they do, they should see if something good will come out of it."

He added: "I will not be talking to SingPost. This (incident) can be seen as one of its publicity stunts.